Conventionally, X-rays are used in a medical device, an industrial device, and a laboratory device. In the medical field, the X-rays are used for chest radiography, dental radiography and CT (Computer Tomogram). In the industrial field, the X-rays are used for nondestructive inspection to observe the interior of a substance such as a structure, a building and a welding part, and for nondestructive tomography inspection. In the research field, the X-rays are used for X-ray diffraction to analyze the crystal structure of a substance, and for X-ray spectroscopy (X-ray fluorescence analysis) to analyze the structural elements of a substance.
The X-rays may be generated with an X-ray tube. The X-ray tube has a pair of electrodes (anode and cathode) therein. An electric current is caused to flow to a cathode filament to heat the cathode filament, and a high voltage is applied across the anode and the cathode. Then, the minus thermo-electrons generated from the filament impinge upon a target on the surface of the anode at a high speed, and the X-rays are generated from the target.
Patent Literature Document 1 (Japanese Patent No. 5694558) discloses that a target on the anode side of the X-ray tube is a liquid metal jet, and the target is irradiated with an electron beam to obtain X-rays at a high luminance.